I tried again to see if I could revive it. I charged the battery (using a bench power supply, set to 4.1V, current-limited at 150mA) for about an hour last night. (I would have left it longer, but at the same time I didn't want to leave it over night.) It looked like the battery retained some charge, as the terminal voltage rose from 3.6V to 3.74V. However, this morning it was down to 3.55V (I left the battery in the kinde.)

My guess is that there's some short-circuit somewhere that drains the battery faster than the internal charging-circuitry can charge it. I have had a look at the accessible parts of the PCB, but I can't find any tin-whiskers, dust-motes or anything like that. I might try to flush it clean with compressed air and-or PCB cleaner, to see if that dislodges something. But if that fails I think I've got a broken PCB on my hands.

At the same time, I'm less and less inclined to spend much more time on it, as my Paperwhite should arrive in a couple of weeks.

The internal charger can control a 30% charge rate (500ma).

Consider first that you have an over-discharged battery. It was at least one time in its life, over discharged.
The failure mode for this type of battery is lose of charge capacity, not loss of ability to charge to its rated terminal voltage.

Remove battery ;
Charge at a 10% rate (150ma) for at least 12 hours ;
Check terminal voltage (when good (above 4.1v), then) ;
Disconnect battery ;
Check its room temperature, self discharge rate (over a couple of days) - it should not have a noticeable self discharge rate over a matter of only a few days ;
Fully recharge ;
Check its room temperature, 1 hour discharge rate, being careful to not let it discharge below 1/2 its (2.2 volts) full-charge terminal voltage.
If it reaches its test limit discharge level (2.2 volts) in less than 30 minutes - it is junk.

The above should qualify the battery as "good" or "time to replace".

Note:
Stop with the cleaning and searching for leakage on the board, you are more likely to do harm than good.
Whatever gave you the idea that a Kindle has a power-off switch?
If it has power applied, at least some parts of the board's electronics is "running".

PS:
It you are tired of playing with it -
Any chance you would like to sell it, as-is, and what part of the world do you live it?
PM me about that.

okay well holding back the switch 15s just literally causes a reboot by cutting the power AFAIK so that sounds right.

Knc1 now knows the most of anyone about the charging logic I would say given his extensive research.

EDIT: Ah *looks up* yeah. him.

I'm firing up my 3 gimme sec...
see if I can grab out some metrics

ENABLE_DIAGS on the user storage partiton + re-boot will give you access to the battery management monitor screen.

NOTE: DO NOT attach to a "wall charger" or other source of greater than 300ma when in this mode - the battery management scripting has a coding error in that will allow an "over-current" charge rate sufficient to damage the USB port.
For the ugly details, find the thread where I cooked my USB port (it has an in-line copy of the battery management report with notes).

ENABLE_DIAGS on the user storage partiton + re-boot will give you access to the battery management monitor screen.

NOTE: DO NOT attach to a "wall charger" or other source of greater than 300ma when in this mode - the battery management scripting has a coding error in that will allow an "over-current" charge rate sufficient to damage the USB port.
For the ugly details, find the thread where I cooked my USB port (it has an in-line copy of the battery management report with notes).

erm. I have never gone into DIAGS on my 3 before...
*trepidation* *cuddles 3 lovingly*

erm. I have never gone into DIAGS on my 3 before...
*trepidation* *cuddles 3 lovingly*

Just avoid the "erase MMC" menu entry.
There is one menu entry that will allow you to "export" the user storage area so that you can delete that ENABLE_DIAGS file. You may have to run some of the tests (to create a tests log file) before you can do the "export".

Those extra battery terminals **should** be I2C - -
But since the device uses an external battery management chip (on one of the SPI buses), then it is unlikely that the battery includes a battery management chip.

Most likely, that I2C connection is just the battery temperature sensor.

That is because to "properly" charge Li-Ion, the battery temperature changes have to be monitored to detect "full charge" condition (you can't use terminal voltage detection to reliably re-charge Li-Ion).

I don't think the battery is quite dead. Or at least it's not the only problem...

I tried to connect an external power supply instead of the battery, but with very limited results. As mentioned above, it keeps consuming power (~120-130mA) but without any on-screen activity. (For at least fifteen minutes.)

Given twobob's figures that sounds like a lot. So, either my flash is corrupted (and the CPU is stuck in an exception loop) or there's something else seriously wrong.

I'm now charging the battery again, but it seems to retain its charge pretty well. (I'm force-feeding it 500mA at 4.1V. I figure that if I do that for an two hours or so it ought to be at least half-charged.)

Quote:

Originally Posted by knc1

It you are tired of playing with it -
Any chance you would like to sell it, as-is, and what part of the world do you live it?

I'll give it another try (or two) before giving up...

I'm in Switzerland, which means that shipping to the US is probably not worth it...

Most likely, that I2C connection is just the battery temperature sensor.

That is because to "properly" charge Li-Ion, the battery temperature changes have to be monitored to detect "full charge" condition (you can't use terminal voltage detection to reliably re-charge Li-Ion).

Yes, that would make sense. They could even use an I2C temperature sensor! (They're pretty cheap, and much easier to use than an analogue interface.)

I charged the battery with 400mA for a couple of hours, then disconnected it and left it overnight. This morning it still showed 4.15V.

I plugged it back in the kindle and the green LED lit up. It booted and went all the way to the 'home screen'! The battery indicator showed 'full' and everything looked OK. Then I picked it up to reassemble the back, and it froze.

My guess is that there's a micro-crack in a trace somewhere, maybe between the CPU and the memory?

I tried to plug it back in a PC, and it shows up as 'SE Blank RINGO' on USB, so I fired up ATK. It recognizes the device, but it won't program it: 'Failed to initial flash or Do not support this Flash'.

I think I've got a broken PCB, but a working battery and screen on my hands. It doesn't bother me overly, as I've got a Paperwhite that should arrive in a couple of weeks, and I've got enough books on paper to survive a minor siege, but it would be nice to have a back-up device.

If Geekmaster's offer of a broken-screen demo unit is still valid, I'd be interested! (If it's possible to make the demo units work, which I gather that it is...)